Polarimetric imaging using a continuously spinning polarizer element

To derive the polarization characteristics of a remotely sensed object, a time-sequential polarimeter must create multiple polarization response states during the course of each measurement set. A common method of creating these states is to rotate a polarizer element to a discrete location and hold that position while the detectors integrate and are sampled. The polarizer element is then rotated to the next position and the process is repeated. This time-sequential, advance-and-hold technique is widely used and easily understood because of its simplicity. However, it is not well suited for remote sensing applications where time delays caused by the advance-and-hold mechanism can limit measurement speed and reduce measurement accuracy. This paper introduces a continuously spinning polarizer (CSP) technique that eliminates the time delays and associated problems of an advance-and-hold polarimeter. A performance model for a linear Stokes polarimeter containing a CSP is derived, and a demonstration of the CSP technique based on the performance of the hyper-spectral imaging polarimeter (HIP) is presented.